Positive photosensitive polyimide resin composition

ABSTRACT

The invention provides a positive photosensitive resin composition which is free from film reduction, swelling or peeling at the time of development with an aqueous alkaline solution and which provides a dimensionally stable patterns after curing, and of which the final cured film has a low water absorption and excellent alkaline resistance. A positive photosensitive polyimide resin composition characterized by comprising an organic solvent-soluble polyimide having repeating units represented by the formula (1):                  
 
(wherein m is an integer of from 3 to 10,000, R 1  is a tetravalent organic group, R 2  is a bivalent organic group, provided that from 5 to 100 mol % of R 2  is a bivalent organic group having fluorine), a polyamic acid and a compound capable of generating an acid by irradiation with light.

TECHNICAL FIELD

The present invention relates to a photosensitive material suitable fora surface protective film, an interlayer insulating film, a passivationfilm, an electrode protecting layer, etc. for e.g. an electric orelectronic device, particularly a semiconductor device or a displaydevice, and particularly, it relates to a positive photosensitivepolyimide resin composition capable of being developed with an aqueousalkaline solution.

BACKGROUND ART

As polyimide type positive photosensitive resin compositions, many havebeen reported wherein a quinonediazido compound is added to a polyamicacid or to a polyamic acid ester or polyimide having an acidic group ina side chain. However, a polyamic acid has a problem such that it issoluble so much in an alkali developer that film reduction at the timeof the development is substantial, and it is necessary to use it by anaddition of an amine or the like (U.S. Pat. No. 4,880,722). On the otherhand, a polyimide (JP-A-3-115461) or polyamic acid ester (JP-A-64-60630)having an acidic group in a side chain is excellent in thedevelopability, etc., but even after curing, acidic groups tend toremain in the polymer, whereby the final cured film was likely to have ahigh water absorption or its alkaline resistance was likely tosubstantially decrease. Further, with a positive photosensitive resinemploying a resin mixture of a polyamic acid and a polyamic acid esterhaving an acidic group has a leaving component (Journal of Applied.Polymer Science, Vol. 51, P. 1971–1978), curing at a higher temperatureis required to convert the polyamic acid ester to a polyimide, and filmreduction by the curing tends to be substantial.

In recent years, use of photosensitive insulating films represented byphotosensitive polyimide resins has been expanded not only to thesemiconductor field but also to the display field. Accordingly, anexcellent resolution free from film reduction or swelling in theformation of fine patterns, adhesion during the development, dimensionalstability of the patterns in high temperature curing, etc. are nowrequired, which have not been required for the conventionalphotosensitive polyimide resins. Among them, JP-A-2001-228609 hasreported a positive photosensitive polyimide resin excellent in adhesionand developability, which comprises an alkali-soluble polyimide, apolyamic acid and an o-quinonediazido compound, but depending upon thecombination of the polyimide and the polyamic acid, there has been acase where whitening of the film or the water absorption of the finalcured film tends to be problematic.

Thus, the conventional positive photosensitive polyimide resins have hadexcellent properties respectively, but on the other hand, it has beendifficult to develop a material which has both the lithographicproperties and the properties for the final cured film and whichprovides patterns having high dimensional stability with little filmreduction or swelling.

The present invention has been made in view of the above-describedcircumstances, and it is intended to provide a positive photosensitiveresin composition which is free from film reduction, swelling or peelingat the time of the development with an aqueous alkaline solution andwhich provides patterns having high dimensional stability after curing,and of which the final cured film has a low water absorption andexcellent alkaline resistance.

DISCLOSURE OF THE INVENTION

The present inventors have conducted an extensive study to solve theabove problems and as a result, have arrived at the present invention.

Namely, the present invention relates to a positive photosensitivepolyimide resin composition characterized by comprising an organicsolvent-soluble polyimide having repeating units represented by theformula (1):

(wherein m is an integer of from 3 to 10,000, R¹ is atetravalent-organic group, R² is a bivalent organic group, provided thatfrom 5 to 100 mol % of R² is a bivalent organic group having fluorine),a polyamic acid having repeating units represented by the formula (2):

(wherein n is an integer of from 3 to 10,000, R³ is a lo tetravalentorganic group, and R⁴ is a bivalent organic group), and a compoundcapable of generating an acid by irradiation with light.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, the present invention will be described in detail.

The composition of the present invention comprises an organicsolvent-soluble polyimide having repeating units represented by theabove formula (1), a polyamic acid having repeating units represented bythe above formula (2) and a compound capable of generating an acid byirradiation with light, whereby etching with an aqueous alkalinesolution is easy, and a polyimide resin coating film having fine anddimensionally highly precise relief patterns can easily be obtained byexposure by means of a mask having prescribed patterns.

The method for obtaining the organic solvent-soluble polyimide havingrepeating units represented by the formula (1), is not particularlylimited. Usually, it is obtained by reacting and polymerizing an organictetracarboxylic acid or its derivative, which constitutes R¹ in theformula (1), with an organic diamine which constitutes R² in the formula(1). Particularly, a method is common wherein an organic tetracarboxylicdianhydride (hereinafter referred to simply as an acid anhydride) and anorganic diamine (hereinafter referred to simply as a diamine) arereacted and polymerized to obtain a polyimide precursor, which issubjected to dehydration ring closure.

The acid anhydride which constitutes R¹ in the formula (1), is notparticularly limited. Further, such acid anhydrides may be used alone orin combination as a mixture of two or more of them.

Specific examples thereof may, for example, be aromatic tetracarboxylicanhydrides such as pyromellitic anhydride,3,3′,4,4′-biphenyltetracarboxylic dianhydride,3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 3,3′,4,4′-diphenylether tetracarboxylic dianhydride,3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride and2,2-bis(3,4-dicarboxyphenyl)hexafluoroisopropylidene dianhydride. Fromthe viewpoint of the solubility, 3,3′,4,4′-biphenyltetracarboxylicdianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride,4,4′-hexafluoroisopropylidene diphthalic anhydride or3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride is, for example,preferred.

Further, alicyclic tetracarboxylic dianhydrides such as1,2,3,4-cyclobutanetetracarboxylic dianhydride,1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride,1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride,1,2,3,4-cyclopentanetetracarboxylic dianhydride,1,2,4,5-cyclohexanetetracarboxylic dianhydride,3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride,5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylicdianhydride, 2,3,5-tricarboxy-2-cyclopentane acetic dianhydride,bicyclo[2.2.2]octo-7-ene-2,3,5,6-tetracarboxylic dianhydride,2,3,4,5-tetrahydrofurane tetracarboxylic dianhydride and3,5,6-tricarboxy-2-norbornane acetic dianhydride, and aliphatictetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylicdianhydride, may, for example, be mentioned.

R¹ in the formula (1) is a tetravalent organic group derived from atetracarboxylic acid, and its structure is not particularly limited.Such organic groups may be of a single type or a mixture of two or moretypes. Specific examples thereof may, for example, be tetravalentorganic groups (of a structure having two anhydride groups fromtetracarboxylic dianhydrides) constituting the above-mentioned acidanhydrides.

Particularly, with a view to increasing the transparency and thesolubility in an organic solvent of the solvent-soluble polyimide resinhaving repeating units represented by the formula (1), a case where fourcarbonyl groups bonded to R¹ are not directly bonded to an aromaticring, or a case where R¹ is a tetravalent organic group constituting anaromatic tetracarboxylic acid having fluorine, is preferred. In order toobtain such a polyimide resin having high transparency and solubility,the acid anhydride which constitutes R¹ in the formula (1) is preferablya tetracarboxylic dianhydride comprising four carbonyl groups notdirectly bonded to an aromatic ring, such as1,2,3,4-cyclobutanetetracarboxylic dianhydride,1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride,1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride,1,2,3,4-cyclopentanetetracarboxylic dianhydride,1,2,4,5-cyclohexanetetracarboxylic dianhydride,3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride,5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylicdianhydride, 2,3,5-tricarboxy-2-cyclopentane acetic dianhydride,bicyclo[2.2.2]octo-7-ene-2,3,5,6-tetracarboxylic dianhydride,2,3,4,5-tetrahydrofurane tetracarboxylic dianhydride or3,5,6-tricarboxy-2-norbornane acetic dianhydride, or an aromaticdianhydride containing fluorine, such as 4,4′-hexafluoroisopropylidenediphthalic anhydride. Likewise, as preferred specific examples for R¹,tetravalent organic groups constituting the above-mentioned acidanhydrides may be mentioned.

Diamines which constitute R² in the formula (1) may be of a single typeor a combination of two or more types, and they are not particularlylimited so long as at least 5 mol % of the diamine component to be used,is a diamine having fluorine. By using from 5 to 100 mol % of a diaminehaving fluorine, from 5 to 100 mol % of R² contained in the finallyobtainable polyimide will be a bivalent organic group having fluorine.Fluorine is effective not only to increase the solubility of the organicsolvent-soluble polyimide but also to improve the compatibility with apolyamic acid. If the diamine component having fluorine is less than 5mol %, i.e. if R² having fluorine in the formula (1) is less than 5 mol%, the compatibility with a polyamic acid is likely to deteriorate,whereby the solution tends to be turbid, or even if the solution willnot be turbid, the surface of a cast film tends to undergo whitening. Itis particularly preferred that from 0 to 100 mol % of R² is a bivalentorganic group having fluorine, and as a diamine to be used, it ispreferred that from 50 to 100 mol % is a diamine having fluorine.

Fluorine in the diamine is usually introduced in the form of e.g. afluoro group or a fluoroalkyl group directly bonded to a benzene ringand may be a singular or plural number. Particularly, from the viewpointof the compatibility with a polyamic acid, a diamine having atrifluoromethyl group or a hexafluoroisopropylidene group, is preferred.Such diamines having fluorine may be used in a single type or incombination of two or more types.

Specific examples of the diamine having a trifluoromethyl group or ahexafluoroisopropylidene group, may, for example, be2,2′-bis(trifluoromethyl)benzidine,2,6,2′,6′-tetrakis(trifluoromethyl)benzidine,2,2-bis[4-(3-aminophenoxy)phenyl]hexafluoropropane,2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane,2,2-bis(4-anilino)hexafluoropropane, 2,2-bis(3-anilino)hexafluoropropaneand 2,2-bis(3-amino-4-toluyl)hexafluoropropane.

R² in the formula (1) is a bivalent organic group derived from adiamine, and its structure is not particularly limited, so long as from5 to 100 mol % of R² is a bivalent organic group having fluorine.Further, R² may be of a single type or a mixture of two or more types.And, R² having fluorine is preferably a bivalent organic group having atrifluoromethyl group or a hexafluoroisopropylidene group, and as itsspecific example, a bivalent organic group (of a structure having twoprimary amino groups removed from a diamine) constituting theabove-mentioned diamine having a trifluoromethyl group or ahexafluoroisopropylidene group.

As the diamine which constitutes R² in the above formula (1), a diaminehaving no fluorine may be used within a range of from 0 to 95 mol %,preferably from 0 to 50 mol %.

The diamine having no fluorine may, for example, be an aromatic diaminesuch as p-phenylenediamine, m-phenylenediamine,2,4,6-trimethyl-1,3-phenylenediamine,2,3,5,6-tetramethyl-1,4-phenylenediamine, 4,4′-diaminodiphenyl ether,3,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether,4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenylmethane,3,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane,4,4′-methylene-bis(2-methylaniline),4,4′-methylene-bis(2,6-dimethylaniline),4,4′-methylene-bis(2,6-diethylaniline),4,4′-methylene-bis(2-isopropyl-6-methylaniline),4,41-methylene-bis(2,6-diisopropylaniline), 4,4′-diaminodiphenylsulfone,3,3′-diaminodiphenylsulfone, benzidine, o-tolidine, m-tolidine,3,3′,5,5′-tetramethylbenzidine, 2,2′-bis(trifluoromethyl)benzidine,1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene,1,3-bis(3-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone,bis[4-(3-aminophenoxy)phenyl]sulfone,2,2-bis[4-(4-aminophenoxy)phenyl]propane or2,2-bis[4-(3-aminophenoxy)phenyl]propane, or an aliphatic diamine suchas 1,6-hexanediamine, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine,1,4-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane,4,4′-diaminodicyclohexylmethane or4,4′-diamino-3,3′-dimethyldicyclohexylmethane. Such diamines having nofluorine may be used in a single type or in combination of two or moretypes.

Specific examples of R² having no fluorine may be bivalent organicgroups constituting the above-mentioned diamines having no fluorine.They may be used in a single type or in combination of two or more typeswithin a range of from 0 to 95 mol %, preferably from 0 to 50 mol %, asmixed to R² of the formula (1).

Further, R² in the formula (1) may have an acidic group, and such acidicgroups may be of one type or a mixture of two or more types.Accordingly, as the diamine which constitutes R² in the formula (1), adiamine having an acidic group may be used. The acidic group may, forexample, be a phenolic hydroxyl group, a carboxylic acid, a sulfoneamidegroup or a sulfonic acid, but as an acidic group for a positivephotosensitive polymer, a carboxylic acid and a phenolic hydroxyl groupare most common. The organic solvent-soluble polyimide having no acidicgroup is insoluble in an alkali developer, but by introducing an acidicgroup, the affinity to the alkali developer will be increased, and ifsuch an acid group is contained to some extent, the dissolution rate inan alkali developer of a film obtainable from the organicsolvent-soluble polyimide, will increase, whereby the time fordevelopment of the positive photosensitive polyimide resin compositionof the present invention can be shortened. However, acidic groups in thepolyimide tend to deteriorate the alkaline resistance of the finallycured film or the film properties such as hygroscopic properties.Accordingly, R² having an acidic group in the formula (1) is preferablyat most 10 mol %. In other words, from 90 to 100 mol % of R² ispreferably a bivalent organic group having no acidic group. Thus, thediamine having an acidic group in the diamine which constitutes R² inthe formula (1) is preferably at most 10 mol %. If it is more than 10mol %, the remaining acidic groups tend to deteriorate the alkalineresistance of the finally cured film or the film properties such ashygroscopic properties.

The positive photosensitive polyimide resin composition of the presentinvention makes it possible to obtain a high contrast between an exposedarea and an unexposed area by a combination of an organicsolvent-soluble polyimide having a low alkali affinity and a polyamicacid having a very high alkali affinity. Accordingly, the organicsolvent-soluble polyimide represented by the formula (1) preferably hasa dissolution rate of at most 0.1 μm/min in a 2.38 wt % tetramethylammonium hydroxide aqueous solution at 23° C. If the dissolution rate isfaster than 0.1 μm/min, not only the contrast deteriorates, but also thesensitivity deteriorates.

The diamine having an acidic group includes a diamine whichsimultaneously has fluorine. Further, R² having an acidic group may be abivalent organic group which has an acidic group and fluorinesimultaneously. In such a case, both the above-mentioned effect havingfluorine and the effect having an acidic group will be provided.

With respect to specific examples of the diamine and R² having an acidicgroup, as a diamine which simultaneously has fluorine, a diamine havinga phenolic hydroxyl group such as2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane,2,2-bis(4-amino-3-hydroxyphenyl)hexafluoropropane,2,2-bis(4-amino-3,5-dihydroxyphenyl)hexafluoropropane or2,2-bis[4-(3-amino-4-hydroxyphenoky)phenyl]hexafluoropropane, or adiamine having a carboxyl group such as2,2-bis[4-(4-amino-3-carboxyphenoxy)phenyl]hexafluoropropane may bementioned; as R² which simultaneously has an acidic group and fluorine,polyvalent organic groups constituting these diamines may be mentioned;as the diamine which has an acidic group and no fluorine, a diaminehaving a phenolic hydroxyl group such as 2,4-diaminophenol,3,5-diaminophenol, 2,5-diaminophenol, 4,6-diaminoresorcinol,2,5-diaminohydroquinone, bis(3-amino-4-hydroxyphenyl)ether,bis(4-amino-3-hydroxyphenyl)ether,bis(4-amino-3,5-dihydroxyphenyl)ether,bis(3-amino-4-hydroxyphenyl)methane,bis(4-amino-3-hydroxyphenyl)methane,bis(4-amino-3,5-dihydroxyphenyl)methane,bis(3-amino-4-hydroxyphenyl)sulfone,bis(4-amino-3-hydroxyphenyl)sulfone,bis(4-amino-3,5-dihydroxyphenyl)sulfone,4,4′-diamino-3,3′-dihydroxybiphenyl,4,4′-diamino-3,3′-dihydroxy-5,5′-dimethylbiphenyl,4,4′-diamino-3,3′-dihydroxy-5,5′-dimethoxybiphenyl,1,4-bis(3-amino-4-hydroxyphenoxy)benzene,1,3-bis(3-amino-4-hydroxyphenoxy)benzene,1,4-bis(4-amino-3-hydroxyphenoxy)benzene,1,3-bis(4-amino-3-hydroxyphenoxy)benzene,bis[4-(3-amino-4-hydroxyphenoxy)phenyl]sulfone orbis[4-(3-amino-4-hydroxyphenoxy)phenyl]propane, or a diamine having acarboxyl group such as 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid,3,5-diaminobenzoic acid, 4,6-diamino-1,3-benzenedicarboxylic acid,2,5-diamino-1,4-benzenedicarboxylic acid,bis(4-amino-3-carboxyphenyl)ether,bis(4-amino-3,5-dicarboxyphenyl)ether,bis(4-amino-3-carboxyphenyl)sulfone,bis(4-amino-3,5-dicarboxyphenyl)sulfone,4,4′-diamino-3,3′-dicarboxybiphenyl,4,4′-diamino-3,3′-dicarboxy-5,5′-dimethylbiphenyl,4,4′-diamino-3,3′-dicarboxy-5,5′-dimethoxybiphenyl,1,4-bis(4-amino-3-carboxyphenoxy)benzene,1,3-bis(4-amino-3-carboxyphenoxy)benzene,bis[4-(4-amino-3-carboxyphenoxy)phenyl]sulfone orbis[4-(4-amino-3-carboxyphenoxy)phenyl]propane, may be mentioned; and asR² which has an acidic group and no fluorine, bivalent organic groupsconstituting such diamines may be mentioned. Diamines having such acidicgroups may be used alone or in combination as a mixture of two or moreof them.

Further, from the viewpoint of adhesion of polyimide as the final curedfilm, a polyimide having a siloxane structure for R² in the formula (1)is preferred, and in order to obtain such a polyimide, it is preferredto employ a diamine constituting R² in the formula (1) in combinationwith a siloxane-containing diamine, but the present invention is notlimited thereto. Further, from the viewpoint of the water absorption ofthe final cured film, R² having a siloxane structure is preferably atmost 10 mol %, and likewise, the amount of the siloxane-containingdiamine is preferably at most 10 mol %.

The siloxane-containing diamine is preferably a siloxane-containingdiamine represented by the formula (3):

(wherein R⁵ is a bivalent organic group, R⁶ is a monovalent organicgroup, and k is an integer of at least 1.)

As preferred specific examples for R² having a siloxane structure,bivalent organic groups which constitute the above-mentionedsiloxane-containing diamines, may be mentioned. The reaction to form apolyimide precursor from an acid anhydride and a diamine, is usuallycarried out in a polar solvent such as N-methylpyrrolidone,dimethylacetamide, γ-butyrolactone or diglyme. The polar solvent to beused here, is not particularly limited so long as it is one capable ofdissolving the polyimide precursor. The reaction temperature of thetetracarboxylic dianhydride with the diamine can be selected to be anoptional temperature from −20 to 150° C., preferably from −5 to 100° C.

To convert the polyimide precursor to a polyimide, the polyimideprecursor may be heated to a temperature of from 150° C. to 250° C. in asolution state, and in order to remove water formed by dehydration ringclosure, it is possible, for example, to add toluene or xylene, followedby azeotropic dehydration.

Further, catalytic imidation may be mentioned as a simple method toconvert the polyimide precursor to a polyimide. In this case, aceticanhydride and a tertiary amine such as triethylamine, pyridine,isoquinoline or imidazole, are added to the polyimide precursor, andimidation may be carried out at an optional temperature of from 0° C. to200° C. This method is known to be an effective method to convert apolyamic acid to a polyimide, since it requires no particular heating orno cumbersome operation to remove water formed by dehydration ringclosure. However, in the case of a polyimide resin containing hydroxylgroups, the hydroxyl groups are likely to react with highly reactiveacetic anhydride, and thus, this method is known to have a drawback thatin such a case, this method can not be employed.

The repeating number m of the organic solvent-soluble polyimide havingrepeating units represented by the formula (1) is an integer of at least3 and at most 10,000. If m is smaller than 3, the mechanical strength ofa film formed by the obtained composition tends to be low, and if m islarger than 10000, the compatibility with the polyamic acid tends tosubstantially deteriorate. Further, a usual polyimide obtained by apolymerization reaction is a collection of molecules having differentpolymerization degrees, and the average value of the repeating number mof the organic solvent-soluble polyimide having repeating unitsrepresented by the formula (1), to be used in the present invention, ispreferably from 10 to 1000, more preferably from 15 to 100.

A method for obtaining a polyamic acid having repeating unitsrepresented by the formula (2) of the present invention, is notparticularly limited.

Usually, it can be obtained by a method wherein an organictetracarboxylic dianhydride which constitutes R³ in the formula (2)(hereinafter referred to simply as an acid anhydride) and an organicdiamine which constitutes R⁴ in the formula (2) (hereinafter referred tosimply as a diamine) are reacted and polymerized.

The acid anhydride which constitutes R³ in the formula (2) is notparticularly limited. Further, such anhydrides may be used alone or incombination as a mixture of two or more of them. As specific examplesthereof, aromatic tetracarboxylic dianhydrides such as pyromelliticanhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride,3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 3,3′,4,4′-diphenylether tetracarboxylic dianhydride,3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride and4,4′-hexafluoroisopropylidenediphthalic anhydride may, for example, bementioned.

Further, an alicyclic tetracarboxylic dianhydride such as1,2,3,4-cyclobutanetetracarboxylic dianhydride,1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride,1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride,1,2,3,4-cyclopentanetetracarboxylic dianhydride,1,2,4,5-cyclohexanetetracarboxylic dianhydride,3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride,5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylicdianhydride, 2,3,5-tricarboxy-2-cyclopentane succinic dianhydride,bicyclo[2.2.2]octo-7-ene-2,3,5,6-tetracarboxylic dianhydride,2,3,4,5-tetrahydrofuranetetracarboxylic dianhydride or3,5,6-tricarboxy-2-norbornane acetic dianhydride, or an aliphatictetracarboxylic dianhydride such as 1,2,3,4-butanetetracarboxylicdianhydride, may be mentioned.

R³ in the formula (2) is a tetravalent organic group derived from atetracarboxylic acid, and its structure is not particularly limited.Such organic groups may be of one type or a mixture of two or moretypes. And, specific examples thereof may be tetravalent organic groupswhich constitute the above-mentioned acid anhydrides.

The diamine which constitutes R⁴ in the formula (2) is not particularlylimited. Further, such diamines may be used alone or in combination as amixture of two or more of them.

Specific examples thereof may be aromatic diamines such asp-phenylenediamine, m-phenylenediamine,2,4,6-trimethyl-1,3-phenylenediamine,2,3,5,6-tetramethyl-1,4-phenylenediamine, 4,4′-diaminodiphenyl ether,3,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether,4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenylmethane,3,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane,4,4′-methylene-bis(2-methylaniline),4,4′-methylene-bis(2,6-dimethylaniline),4,4′-methylene-bis(2,6-diethylaniline),4,4′-methylene-bis(2-isopropyl-6-methylaniline),4,4′-methylene-bis(2,6-diisopropylaniline), 4,4′-diaminodiphenylsulfone,3,3′-diaminodiphenylsulfone, benzidine, o-tolidine, m-tolidine,3,3′,5,5′-tetramethylbenzidine, 2,2′-bis(trifluoromethyl)benzidine,1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene,1,3-bis(3-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone,bis[4-(3-aminophenoxy)phenyl]sulfone,2,2-bis[4-(4-aminophenoxy)phenyl]propane,2,2-bis[4-(3-aminophenoxy)phenyl]propane,2,2-bis[4-(3-aminophenoxy)phenyl]hexafluoropropane,2,2-bis(4-anilino)hexafluoropropane, 2,2-bis(3-anilino)hexafluoropropaneand 2,2-bis(3-amino-4-toluyl)hexafluoropropane. Further, aliphaticdiamines such as 1,6-hexanediamine, 1,4-cyclohexanediamine,1,3-cyclohexanediamine, 1,4-bis(aminomethyl)cyclohexane,1,3-bis(aminomethyl)cyclohexane, 4,4′-diaminodicyclohexylmethane and4,4′-diamino-3,3′-dimethyldicyclohexylmethane, may be mentioned.

R⁴ in the formula (2) is a bivalent organic group derived from adiamine, and its structure is not particularly limited. Such organicgroups may be of one type or a mixture of two or more types.Accordingly, specific examples thereof may be bivalent organic groupswhich constitute the above-mentioned diamines.

Further, from the viewpoint of the adhesion of a polyimide as the finalcured film, a polyamic acid having a siloxane structure for R⁴ in theformula (2) is preferred, and in order to obtain such a polyimide, it ispreferred to employ also a siloxane-containing diamine in combination,as the diamine which constitutes R⁴ in the formula (2), but the presentinvention is not limited thereto. Further, from the viewpoint of thewater absorption of the final cured film, R⁴ having a siloxane structureis preferably at most 10 mol %, and likewise, the amount of thesiloxane-containing diamine is preferably at most 10 mol %.

As the siloxane-containing diamine, a siloxane-containing diaminerepresented by the formula (3):

(wherein R⁵ is a bivalent organic group, R⁶ is a monovalent organicgroup, and k is an integer of at least 1) is preferred.

A preferred specific example of R⁴ having a siloxane structure may be abivalent organic group which constitutes the above-mentionedsiloxane-containing diamine.

As described above, in the polyamic acid having repeating unitsrepresented by the formula (2), the structures of R³ and R⁴ are notparticularly limited, but from the viewpoint of the water absorption ofthe final cured film, it is preferred that at least one of R³ and R⁴ hasfluorine. In order to obtain such a polyamic acid, an acid anhydridehaving fluorine may be used as the acid anhydride which constitutes R³in the formula (2), or a diamine having fluorine may be used as thediamine which constitutes R in the formula (2). As a specific example ofthe acid anhydride having fluorine, 4,4′-hexafluoroisopropylidenediphthalic anhydride may be mentioned, and as the diamine havingfluorine, 2,2′-bis(trifluoromethyl)benzidine,2,6,2′,6′-tetrakis(trifluoromethyl)benzidine,2,2-bis[4-(3-aminophenoxy)phenyl]hexafluoropropane,2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane,2,2-bis(4-anilino)hexafluoropropane, 2,2-bis(3-anilino)hexafluoropropaneor 2,2-bis(3-amino-4-toluyl)hexafluoropropane may be mentioned. As apreferred example of R³ having fluorine, a tetravalent organic groupconstituting the above-mentioned acid anhydride having fluorine may bementioned, and as a preferred example of R⁴ having fluorine, a bivalentorganic group constituting the above-mentioned diamine having fluorinemay be mentioned.

With respect to the preferred contents of R³ having fluorine and R⁴having fluorine in the formula (2), R³ having fluorine to the total R³is preferably from 50 to 100 mol %, or R⁴ having fluorine to the totalR⁴ is from 50 to 100 mol %, or the sum of the molar ratio of R³ havingfluorine to the total R³ and the molar ratio of R⁴ having fluorine tothe total R⁴, is from 50 to 100 mol %. If the sum of the molar ratio ofR³ having fluorine to the total R³ and the molar ratio of R⁴ havingfluorine to the total R⁴, is larger than 100 mol %, wettability to asubstrate tends to be poor when used as a coating fluid, and uniformityof the coating film or adhesion to the substrate tends to be poor.

The reaction to obtain a polyamic acid from an acid anhydride and adiamine is carried out usually in a polar solvent such asN-methylpyrrolidone, dimethylacetamide, γ-butyrolactone or diglyme. Thepolar solvent to be used here, is not particularly limited so long as itis one capable of dissolving the polyimide precursor. The reactiontemperature of the tetracarboxylic dianhydride with the diamine can beselected to be an optional temperature from −20 to 150° C., preferablyfrom −5 to 100° C.

In the present invention, the repeating number n of the polyamic acidhaving repeating units represented by the formula (2) is an integer offrom 3 to 10000. If n is smaller than 3, the mechanical strength of afilm to be formed by the obtained composition tends to be low, and if nis larger than 10000, the compatibility with a solvent-soluble polyimidetends to be very low. Further, a polyimide obtainable by a usualpolymerization reaction is a collection of molecules having differentpolymerization degrees, and accordingly, the average value of therepeating number m of the organic solvent-soluble polyimide havingrepeating units represented by the formula (2) to be used in the presentinvention is preferably from 10 to 1000, more preferably from 15 to 100.

In the present invention, the compound capable of generating an acid byirradiation with light, is not particularly limited so long as it is onewhich is capable of generating an acid by a photoreaction and which hasa function to increase the solubility of the irradiated portion in analkali developer. Further, such compounds may be used alone or incombination as a mixture of two or more of them.

Specific examples thereof may, for example, be an o-quinonediazidecompound, an allyl diazonium salt, a diallyl iodonium salt, a triallylsulfonium salt, an o-nitrobenzyl ester, a p-nitrobenzyl ester, atrihalomethyl group-substituted s-triazine derivative and an imidesulfonate derivative. Further, a sensitizing agent may be used incombination, as the case requires. The sensitizing agent may, forexample, be perylene, anthracene, thioxanthene, Micheler's ketone,benzophenone or fluorine.

Among such compounds capable of generating acids by irradiation withlight, an o-quinonediazide compound is preferred from the viewpoint ofthe sensitivity and resolving power.

Usually, the o-quinonediazide compound is used in the form of ano-quinonediazide sulfonic acid ester or an o-quinonediazide sulfoneamide, obtainable by a condensation reaction of ano-quinonediazidesulfonyl chloride with a compound having a hydroxylgroup or a compound having an amino group in the presence of a basiccatalyst.

As the o-quinonediazide sulfonic acid component which constitutes theabove o-quinonediazidesulfonyl chloride,1,2-naphthoquinone-2-diazido-4-sulfonic acid,1,2-naphthoquinone-2-diazido-5-sulfonic acid or1,2-naphthoquinone-2-diazido-6-sulfonic acid, may, for example, bementioned.

The above compound having a hydroxyl group, may, for example, be aphenol compound such as phenol, o-cresol, m-cresol, p-cresol,hydroquinone, resorcinol, catechol, 4,4-isopropylidenediphenol,1,1-bis(4-hydroxyphenyl)cyclohexane, 4,4′-dihydroxyphenylsulfone,4,4-hexafluoroisopropylidenediphenol,4,4′,4″-trihydroxytriphenylmethane, 1,1, 1-tris(4-hydroxyphenyl)ethane,4,4′-[1-[4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl]ethylidene]bisphenol,2,4-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone,2,2′,4,4′-tetrahydroxybenzophenone, 2,3,4,4′-tetrahydroxybenzophenone or2,3,4,2′,4′-pentahydroxybenzophenone, or an aliphatic alcohol such asethanol, 2-propanol, 4-butanol, cyclohexanol, ethylene glycol, propyleneglycol, diethylene glycol, dipropylene glycol, 2-methoxyethanol,2-butoxyethanol, 2-methoxypropanol, 2-butoxypropanol, ethyl lactate orbutyl lactate.

Further, an aniline such as aniline, o-toluidine, m-toluidine,p-toluidine, 4-aminodiphenylmethane, 4-aminodiphenyl,o-phenylenediamine, m-phenylenediamine, p-phenylenediamine,4,4′-diaminodiphenylmethane or 4,4′-diaminodiphenylether, oraminocyclohexane, may be mentioned.

Further, as the compound having both a hydroxyl group and an aminogroup, an aminophenol such as o-aminophenol, m-aminophenol,p-aminophenol, 4-aminoresorcinol, 2,3-diaminophenol, 2,4-diaminophenol,4,4′-diamino-4″-hydroxytriphenylmethane,4-amino-4′,4″-dihydroxytriphenylmethane,bis(4-amino-3-carboxy-5-hydroxyphenyl)ether,bis(4-amino-3-carboxy-5-hydroxyphenyl)methane,bis(4-amino-3-carboxy-5-hydroxyphenyl)sulfone,2,2-bis(4-amino-3-carboxy-5-hydroxyphenyl)propane or2,2-bis(4-amino-3-carboxy-5-hydroxyphenyl)hexafluoropropane, or analkanol amine such as 2-aminoethanol, 3-aminopropanol or4-aminocyclohexanol, may be mentioned.

It is common to employ such compounds in the form of di-substitutedcompounds, tri-substituted compounds, tetra-substituted compounds orpenta-substituted compounds having part or all of hydroxyl groups oramino groups of such compounds substituted by the above o-quinonediazidosulfonic acid groups, or in the form of a mixture thereof.

In the positive photosensitive polyimide resin composition of thepresent invention, the incorporated amounts of the organicsolvent-soluble polyimide having repeating units represented by theformula (1) and the polyamic acid having repeating units represented bythe formula (2), are preferably such that the latter is from 5 to 400parts by weight per 100 parts by weight of the former, from theviewpoint of the sensitivity, resolving power and developability. If thepolyamic acid per 100 parts by weight of the organic solvent-solublepolyimide is less than 5 parts by weight, the developability of theexposed area of the positive photosensitive resin composition film tendsto be poor, and not only the contrast between the exposed area and theunexposed area tends to be small, but the sensitivity tends todeteriorate. On the other hand, if the polyamic acid per 100 parts byweight of the organic solvent-soluble polyimide exceeds 400 parts byweight, the developer resistance of the exposed area of the positivephotosensitive resin composition film tends to be extremely low, wherebythe film reduction of the pattern after the development tends to besubstantial, and the resolving power will also decrease. It isparticularly preferred that the polyamic acid per 100 parts by weight ofthe organic solvent-soluble polyimide, is from 50 to 200 parts byweight.

Further, from the viewpoint of the sensitivity and the resolving powerof the positive photosensitive polyimide resin composition and thecharacteristics of the film after baking, the compound capable ofgenerating an acid by irradiation with light, is preferably from 1 to 50parts by weight per 100 parts by weight of the total amount of the aboveorganic solvent-soluble polyimide and the polyamic acid. If the compoundcapable of generating an acid by irradiation with light per 100 parts byweight of the total amount of the organic solvent-soluble polyimide andthe polyamic acid, is less than 1 part by weight, the solubility in analkali developer of the exposed area of the positive photosensitiveresin composition film tends to be inadequate, whereby the contrastbetween the exposed area and the unexposed area tends to be small. Onthe other hand, if the compound capable of generating an acid byirradiation with light per 100 parts by weight of the total amount ofthe organic solvent-soluble polyimide and the polyamic acid, exceeds 50parts by weight, the mechanical properties of a cured film obtained bytreating the positive photosensitive resin composition film at a hightemperature, tends to deteriorate. Especially, the compound capable ofgenerating an acid by irradiation with light is preferably from 10 to 40parts by weight, per 100 parts by weight of the total amount of theorganic solvent-soluble polyimide and the polyamic acid.

When employed for an electric or electronic device, the positivephotosensitive polyimide resin composition of the present invention isused in the form of a solution as dissolved in an organic solvent. Suchan organic solvent is not particularly limited so long as it is onewherein the polyimide, the polyamic acid and the compound capable ofgenerating an acid by irradiation with light can be uniformly dissolved,and such components are compatibly soluble. Specific examples thereofmay, for example, be N,N-dimethylformamide, N,N-dimethylacetamide,N-methyl-2-pyrrolidone, N-vinyl pyrrolidone, dimethylsulfoxide,γ-butyrolactone and cyclohexanone.

Further, another organic solvent may be used in combination as the caserequires, so long as the present composition can be uniformly dissolved.Specific examples of such an organic solvent may, for example, be2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-methoxyethylacetate, 2-methoxy-1-propanol, 3-methoxypropyl acetate, ethyl lactate,butyl lactate, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butylcarbitol, ethyl carbitol acetate, butyl carbitol acetate and ethyleneglycol.

As a method to obtain a solution of the positive photosensitivepolyimide resin composition of the present invention, a solution of thepolyamic acid having repeating units represented by the formula (2) andthe compound capable of generating an acid by irradiation with light maybe dissolved in a solution having the organic solvent-soluble polyimidehaving repeating units represented by the formula (1) reacted andpolymerized, or the organic solvent-soluble polyimide resin havingrepeating units represented by the formula (1), precipitated andrecovered by means of a poor solvent, and the polyamic acid havingrepeating units represented by the formula (2) may be dissolved in theabove-mentioned organic solvent, together with the compound capable ofgenerating an acid by irradiation with light.

The concentration of the above resin composition solution is notparticularly limited so long as the respective components are uniformlydissolved. From the efficiency in processing, it is usually preferablyused within a range of from 1 to 50 wt %, particularly preferably from 5to 30 wt %.

The positive photosensitive polyimide resin composition of the presentinvention may further contain an organic silane compound or an aluminumchelate compound in order to improve the adhesion to the substrate of acured film.

The organic silane compound may, for example, be vinyl triethoxysilane,3-glycidoxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilaneor 3-aminopropyltriethoxysilane. The aluminum chelate compound may, forexample, be tris(acetyl acetonate)aluminum or acetyl acetate aluminumdiisopropylate.

The solution of the positive photosensitive polyimide resin compositionof the present invention may be spin-coated on a substrate such as asilicon wafer, an oxide film or a nitride film, followed by preliminarydrying at a temperature of from 80 to 130° C. to form a film.

On the above film, a mask having a prescribed pattern in mounted, and alight is irradiated, followed by development with an alkali developer,whereby the exposed area is washed off to obtain a relief pattern havinga sharp edge surface. The developer to be used here may be any developerso long as it is an aqueous alkaline solution, and an aqueous solutionof an alkali metal hydroxide such as potassium hydroxide, sodiumhydroxide, potassium carbonate or sodium carbonate, an aqueous solutionof a quaternary ammonium hydroxide such as tetramethyl ammoniumhydroxide, tetraethyl ammonium hydroxide or an aqueous solution of anamine such as ethanolamine, propylamine or ethylene diamine, may, forexample, be mentioned.

The above alkali developer is usually an aqueous solution of at most 10wt %, preferably an aqueous solution of from 0.5 to 3.0 wt %. Further,to the above developer, an alcohol and a surfactant may be added foruse. They may, respectively, be incorporated preferably within a rangeof from 0.05 to 10 parts by weight, per 100 parts by weight of thedeveloper.

With the present composition, the solubility of the exposed area ishigh, and the above development can easily be carried out at roomtemperature.

The substrate having a relief pattern thus obtained, is subjected toheat treatment at a temperature of from 180 to 400° C., whereby it ispossible to obtain a polyimide coating film having a good reliefpattern, which is excellent in heat resistance, chemical resistance andelectrical characteristics.

The composition of the present invention has positive photosensitivecharacteristics with high sensitivity and high resolution, wherebyetching with an aqueous alkaline solution is easy, and by exposure bymeans of a mask having a prescribed pattern, a polyimide resin coatingfilm having a relief pattern having a fine shape and high dimensionalprecision, can easily be obtained.

The positive photosensitive polyimide resin composition of the presentinvention may be used for e.g. an interlayer insulating film for asemiconductor element, a passivation film, a buffer coating film or aninsulating film for a multilayer printed circuit board. Further, it mayalso be used for a protective film for a thin film transistor of aliquid crystal display device, or a protective film for electrodes foran inorganic EL device.

Now, the present invention will be described in further detail withreference to Examples. However, it should be understood that the presentinvention is by no means restricted thereto.

PREPARATION EXAMPLE 1 Preparation of Organic Solvent-Soluble Polyimide(1)

16.30 g (0.045 mol) of 2,2′-bis(3-amino-4-toluyl)hexafluoropropane(hereinafter referred to simply as BIS-AT-AF), 0.76 g (0.005 mol) of3,5-diamino benzoic acid (hereinafter referred to simply as DABA) and9.81 g (0.050 mol) of cyclobutanetetracarboxylic dianhydride(hereinafter referred to simply as CBDA) were dissolved in 62.70 g ofN-methyl-2-pyrrolidone (hereinafter referred to simply as NMP), and areaction was carried out at room temperature for 24 hours.

To the reaction solution, 246.30 g of NMP, 51.05 g (0.500 mol) of aceticanhydride and 39.55 g (0.300 mol) of pyridine were added, and adehydration ring closure reaction was carried out at 40° C. for 3 hours.This solution was put into pure water, followed by filtration and dryingto obtain 23.70 g of a powdery organic solvent-soluble polyimide (1)having a number average molecular weight of 26,100 as calculated aspolyethylene oxide (the average of repeating units was about 49).

The polyimide (1) was dissolved in NMP, directly coated on a siliconwafer by means of a spin coater and heated at 120° C. for two minutes ona hotplate to obtain a coating film having a thickness of about 2.0 μm.This coating film was immersed in a 2.38 wt % tetramethylammoniumhydroxide aqueous solution (hereinafter referred to as TMAH) at 23° C.for from 60 to 180 seconds, whereby the dissolution rate was measuredand found to be 0.06 μm/min.

PREPARATION EXAMPLE 2 Preparation of Organic Solvent-Soluble Polyimide(2)

15.76 g (0.044 mol) of BIS-AT-AF, 0.61 g (0.004 mol) of DABA, 0.62 g(0.002 mol) of bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane(hereinafter referred to simply as APDS) and 9.81 g (0.050 mol) of CBDAwere dissolved in 62.53 g of NMP, and a reaction was carried out at roomtemperature for 24 hours.

To the reaction solution, 245.67 g of NMP, 51.05 g (0.500 mol) of aceticanhydride and 39.55 g (0.300 mol) of pyridine were added, and adehydration ring closure reaction was carried out at 40° C. for 3 hours.This solution was put into pure water, followed by filtration and dryingto obtain 27.55 g of a powdery organic solvent-soluble polyimide (2)having a number average molecular weight of 21,200 as calculated aspolyethylene oxide (the average of repeating units was about 40). Thedissolution rate of the polyimide (2) was measured in the same manner asin Preparation Example 1 and found to be 0.05 μm/min.

PREPARATION EXAMPLE 3 Preparation of Organic Solvent-Soluble Polyimide(3)

18.12 g (0.050 mol) of BIS-AT-AF and 9.81 g (0.050 mol) of CBDA weredissolved in 65.17 g of NMP, and a reaction was carried out at roomtemperature for 24 hours.

To the reaction solution, 256.03 g of NMP, 51.05 g (0.500 mol) of aceticanhydride and 39.55 g (0.300 mol) of pyridine were added, and adehydration ring closure reaction was carried out at 40° C. for 3 hours.This solution was put into pure water, followed by filtration and dryingto obtain 23.18 g of a powdery organic solvent-soluble polyimide (3)having a number average molecular weight of 26,000 (the average ofrepeating units was about 47). The dissolution rate of the polyimide (3)was measured in the same manner as in Preparation Example 1 and found tobe 0.00 μm/min.

PREPARATION EXAMPLE 4 Preparation of Organic Solvent-Soluble Polyimide(4)

16.01 g (0.050 mol) of 2,2′-bis(trifluoromethyl)benzidine (hereinafterreferred to simply as TFMB) and 13.21 g (0.050 mol) of5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylicdianhydride were dissolved in 68.18 g of NMP, and a reaction was carriedout at room temperature for 36 hours.

To the reaction solution, 267.85 g of NMP, 51.05 g (0.500 mol) of aceticanhydride and 39.55 g (0.300 mol) of pyridine were added, and adehydration ring closure reaction was carried out at 40° C. for 3 hours.This solution was put into pure water, followed by filtration and dryingto obtain 26.30 g of a powdery organic solvent-soluble polyimide (4)having a number average molecular weight of 15,900 as calculated aspolyethylene oxide (the average of repeating units was about 27). Thedissolution rate of the polyimide (4) was measured in the same manner asin Preparation Example 1 and found to be 0.00 μm/min.

PREPARATION EXAMPLE 5 Preparation of Organic Solvent-Soluble Polyimide(5)

15.14 g (0.035 mol) of bis[4-(3-aminophenoxy)phenyl]sulfone, 2.28 g(0.015 mol) of DABA and 9.61 g (0.049 mol) CBDA were reacted in 153.17 gof NMP at room temperature for 6 hours.

To the reaction solution, 157.67 g of NMP, 51.05 g (0.500 mol) of aceticanhydride and 39.55 g (0.300 mol) of pyridine were added, and adehydration ring closure reaction was carried out at 40° C. for 3 hours.This solution was put into pure water, followed by filtration and dryingto obtain 24.33 g of a powdery organic solvent-soluble polyimide (5)having a number average molecular weight of 36,000 as calculated aspolyethylene oxide (the average of repeating units was about 66). Thedissolution rate of the polyimide (5) was measured in the same manner asin Preparation Example 1 and found to be 0.20 μm/min.

PREPARATION EXAMPLE 6 Preparation of Polyamic Acid solution (6)

15.21 g of TFMB, 0.62 g of APDS and 14.42 g of3,3′,4,4′-biphenyltetracarboxylic dianhydride (hereinafter referred tosimply as BPDA) were reacted in 171.41 g of NMP at room temperature for12 hours, to obtain an NMP solution of a polyamic acid (6). The numberaverage molecular weight was 19,500 as calculated as polyethyleneoxide(the average of repeating units was about 32).

PREPARATION EXAMPLE 7 Preparation of Polyamic Acid Solution (7)

15.21 g of TFMB, 0.62 g of APDS, 6.99 g of BPDA and 5.18 g ofpyromellitic anhydride (hereinafter referred to simply as PMDA) werereacted in 158.67 g of NMP at room temperature for 12 hours, to obtainan NMP solution of a polyamic acid (7). The number average molecularweight was 20,500 as calculated as polyethylene oxide (the average ofrepeating units was about 36).

PREPARATION EXAMPLE 8 Preparation of Polyamic Acid Solution (8)

15.21 g of TFMB, 0.62 g of APDS and 10.14 g of PMDA were reacted in147.16 g of NMP at room temperature for 12 hours, to obtain an NMPsolution of a polyamic acid (8). The number average molecular weight was19,500 as calculated as polyethylene oxide (the average of repeatingunits was about 36).

PREPARATION EXAMPLE 9 Preparation of Polyamic Acid Solution (9)

9.41 g of 4,4′-diaminodiphenylmethane (hereinafter referred to simply asDDM), 0.62 g of APDS and 21.32 g of 4,4′-hexafluoroisopropylidenediphthalic anhydride (hereinafter referred to simply as 6FDA) werereacted in 177.65 g of NMP at room temperature for 12 hours, to obtainan NMP solution of a polyamic acid (9). The number average molecularweight was 19,000 as calculated as polyethylene oxide (the average ofrepeating units was about 29).

EXAMPLE 1

1.80 g of the solvent-soluble polyimide resin (1) was dissolved in asolvent mixture comprising 7.83 g of ethyl lactate (hereinafter referredto simply as EL) and 11.47 g of NMP, and 8.00 g of the polyamic acidsolution (6) was added and mixed to obtain a solution, to which 0.90 gof a photosensitive material prepared by a condensation reaction of 1mol of 4,4′-[1-[4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl]ethylidene]with 2 mol of 1,2-naphthoquinone-2-diazido-5-sulfonyl chloride (P-200,manufactured by Toyo Gosei Kogyo Co., Ltd.) was added, followed bystirring at room temperature for 1 hour and then by filtration by meansof a filter of 0.2 μm, to obtain a solution of a positive photosensitivepolyimide resin composition.

This solution was directly coated on a silicon wafer by means of a spincoater and heated at 120° C. for two minutes on a hotplate to obtain acoating film having a thickness of about 1.0 μm. To this coating film,ultraviolet light was irradiated for 15 seconds through a test mask bymeans of an ultraviolet irradiation apparatus PLA-501 manufactured byCanon Inc. After the exposure, development was carried out by immersionfor 45 seconds in a 2.38% TMAH aqueous solution (NMD-3, manufactured byTokyo Ohka K.K.) at 23° C. The film thickness after the development wasabout 1.0 μm, whereby no film reduction was observed. The patternresolution was such that the pattern was formed up to a line/space of 3μm without peeling of the pattern.

This pattern was heated at a high temperature of 250° C. for 30 minutesin a circulating drying furnace, whereby the remaining film thicknessratio was 80%, and no substantial dimensional change of the pattern wasobserved.

Further, in the same manner as above, the coating film of thephotosensitive polyimide resin composition formed on the silicon waferwas heated at a high temperature of 250° C. for 30 minutes in acirculating drying furnace and then immersed in pure water maintained at23° C. for 24 hours. This coating film was measured by athermogravimetric analyzer TG-DTA manufactured by MAC Science Co., Ltd.,whereby the water absorption of the coating film was 2.2%.

EXAMPLE 2

A solution of a positive photosensitive polyimide resin composition wasobtained in the same manner as in Example 1 except that thesolvent-soluble polyimide resin (1) was changed to the solvent-solublepolyimide resin (2).

This solution was directly coated on a silicon wafer by means of a spincoater and heated at 120° C. for two minutes on a hotplate to obtain acoating film having a thickness of about 1.0 μm. To this coating film,ultraviolet light was irradiated for 15 seconds through a test mask bymeans of PLA-501. After the exposure, development was carried out byimmersion in NMD-3 at 23° C. for 40 seconds. The film thickness afterthe development was about 1.0 μm, and no film reduction was observed.The pattern resolution was such that the pattern was formed up to aline/space of 3 μm without peeling of the pattern.

This pattern was heated at a high temperature of 250° C. for 30 minutesin a circulating drying furnace, whereby the remaining film thicknessratio was 80%, and the dimensional change of the pattern was a practicallevel. Further, the water absorption was measured in the same manner asin Example 1 and found to be 1.7%.

EXAMPLE 3

A solution of a positive photosensitive polyimide resin composition wasobtained in the same manner as in Example 1 except that the polyamicacid solution (6) was changed to the polyamic acid solution (9).

This photosensitive polyimide solution was directly coated on a siliconwafer by means of a spin coater and heated at 120° C. for two minutes ona hotplate to obtain a coating film having a thickness of about 1.0 μm.To this coating film, ultraviolet light was irradiated for 15 secondsthrough a test mask by means of PLA-501. After the exposure, developmentwas carried out by immersion in NMD-3 at 23° C. for 60 seconds. The filmthickness after the development was about 1.0 μm, and no film reductionwas observed. The pattern resolution was such that the pattern wasformed up to a line/space of 5 μm without peeling of the pattern.

This pattern was heated at a high temperature of 250° C. for 30 minutesin a circulating drying furnace, whereby the remaining film thicknessratio was 82%, and the dimensional change of the pattern was a practicallevel. Further, the water absorption was measured in the same manner asin Example 1 and found to be 1.9%.

EXAMPLE 4

A solution of a positive photosensitive polyimide resin composition wasobtained in the same manner as in Example 1 except that thesolvent-soluble polyimide resin (1) was changed to the solvent-solublepolyimide resin (3), and the polyamic acid solution (6) was changed tothe polyamic acid solution (7).

This photosensitive polyimide solution was directly coated on a siliconwafer by means of a spin coater and heated at 1200C for two minutes on ahotplate to obtain a coating film having a thickness of about 1.0 μm. Tothis coating film, ultraviolet light was irradiated for 15 secondsthrough a test mask by means of PLA-501. After the exposure, developmentwas carried out by immersion in NMD-3 at 23° C. for 60 seconds. The filmthickness after the development was about 1.0 μm, and no film reductionwas observed. The pattern resolution was such that the pattern wasformed up to a line/space of 3 μm without peeling of the pattern.

This pattern was heated at a high temperature of 250° C. for 30 minutesin a circulating drying furnace, whereby the remaining film thicknessratio was 80%, and the dimensional change of the pattern was a practicallevel. Further, the water absorption was measured in the same manner asin Example 1 and found to be 1.4%.

EXAMPLE 5

1.20 g of the solvent-soluble polyimide resin (4) was dissolved in asolvent mixture comprising 7.83 g of EL and 7.47 g of NMP, and 12.00 gof the polyamic acid solution (8) was further added and mixed to obtaina solution, to which 0.90 g of P-200 was added, followed by stirring atroom temperature for 3 hour and then by filtration by means of a filterof 0.2 μm, to obtain a solution of a positive photosensitive polyimideresin composition.

This photosensitive polyimide solution was directly coated on a siliconwafer by means of a spin coater and heated at 120° C. for two minutes ona hotplate to obtain a coating film having a thickness of about 1.0 μm.To this coating film, ultraviolet light was irradiated for 15 secondsthrough a test mask by means of PLA-501. After the exposure, developmentwas carried out by immersion in NMD-3 at 23° C. for 60 seconds. The filmthickness after the development was about 1.0 μm, and no film reductionwas observed. The pattern resolution was such that the pattern wasformed up to a line/space of 5 μm without peeling of the pattern.

This pattern was heated at a high temperature of 250° C. for 30 minutesin a circulating drying furnace, whereby the remaining film thicknessratio was 78%, and the dimensional change of the pattern was a practicallevel. Further, the water absorption was measured in the same manner asin Example 1 and found to be 0.8%.

COMPARATIVE EXAMPLE 1

3 g of the solvent-soluble polyimide resin (2) was added and mixed to asolvent mixture comprising 7.83 g of EL and 18.27 g of NMP to obtain asolution, to which 0.90 g of P-200 was added, followed by stirring atroom temperature for one hour and then by filtration by means of afilter of 0.2 μm, to obtain a solution of a positive photosensitiveresin composition.

This photosensitive polyimide solution was directly coated on a siliconwafer by means of a spin coater and heated at 120° C. for 3 minutes on ahotplate to obtain a coating film having a thickness of about 1.0 μm. Tothis coating film, ultraviolet light was irradiated for 15 secondsthrough a test mask by means of PLA-501. After the exposure, developmentwas carried out by immersion in NMD-3 at 23° C. for 180 seconds, but atthe exposed area, the remaining film was observed, and a pattern was notobtained. Further, the water absorption was measured in the same manneras in Example 1 and found to be 1.9%.

COMPARATIVE EXAMPLE 2

To 20.00 g of the polyamic acid solution (6), 7.83 g of EL and 1.27 g ofNMP were added and mixed to obtain a solution, to which 0.90 g of P-200was added, followed by stirring at room temperature for one hour andthen by filtration by means of a filter of 0.2 μm, to obtain a solutionof a positive photosensitive resin composition.

This photosensitive polyimide solution was directly coated on a siliconwafer by means of a spin coater and heated at 120° C. for two minutes ona hotplate to obtain a coating film having a thickness of about 1.0 μm.To this coating film, ultraviolet light was irradiated for 15 secondsthrough a test mask by means of PLA-501. After the exposure, developmentwas carried out by immersion in NMD-3 at 23° C. for 20 seconds, wherebyunexposed area was also dissolved, and a pattern was not obtained.Further, the water absorption was measured in the same manner as inExample 1 and found to be 0.8%.

COMPARATIVE EXAMPLE 3

3 g of the solvent-soluble polyimide resin (5) was added and mixed to asolvent mixture comprising 17.55 g of γ-butyrolactone and 17.55 g of NMPto obtain a solution, to which 0.90 g of a photosensitive materialprepared by a condensation reaction of 1 mol of2,3,4,4′-tetrahydroxybenzophenone with 3 mol of1,2-naphthoquinone-2-diazido-5-sulfonyl chloride (4NT-300, manufacturedby Toyo Gosei Kogyo Co., Ltd.) was added, followed by stirring at roomtemperature for one hour and then by filtration by means of a filter of0.2 μm, to obtain a solution of a positive photosensitive resincomposition.

This photosensitive polyimide solution was directly coated on a siliconwafer by means of a spin coater and heated at 120° C. for 3 minutes on ahotplate to obtain a coating film having a thickness of about 1.0 μm. Tothis coating film, ultraviolet light was irradiated for 35 secondsthrough a test mask by means of PLA-501. After the exposure, developmentwas carried out by immersion in NMD-3 at 23° C. for 150 seconds. Thefilm thickness after the development was about 0.97 μm, and the filmreduction was slight. However, peeling of the pattern was observed witha line/space being 30 μm or less.

This pattern was heated at a high temperature of 250° C. for 30 minutesin a circulating drying furnace, whereby the remaining film thicknessratio was 82%, and the dimensional change of the pattern was a practicallevel. Further, the water absorption was measured in the same manner asin Example 1 and found to be at least 3%.

COMPARATIVE EXAMPLE 4

1.80 g of the solvent-soluble polyimide resin (5) was dissolved in asolvent mixture comprising 7.55 g of γ-butyrolactone and 10.75 g of NMP,and 8.00 g of the polyamic acid solution (6) was further added and mixedto obtain a solution, to which 0.90 g of P-200 was added, followed bystirring at room temperature for one hour and then by filtration bymeans of a filter of 0.2 μm, to obtain a solution of a positivephotosensitive polyimide resin composition.

This photosensitive polyimide solution was directly coated on a siliconwafer by means of a spin coater and heated at 120° C. for 3 minutes on ahotplate, whereby it was possible only to obtain a coating film having anon-uniform surface with a turbid appearance.

TABLE 1 Weight Polyamic Weight Photo- Polyimide ratio acid ratiosensitive component (%) component (%) material * Ex. 1 (1) 60 (6) 40P-200 2 (2) 60 (6) 40 P-200 3 (1) 60 (9) 40 P-200 4 (3) 60 (7) 40 P-2005 (4) 40 (8) 60 P-200 Comp. 1 (2) 100 — 0 P-200 Ex. 2 — 0 (6) 100 P-2003 (5) 100 — 0 4NT-300 4 (5) 60 (6) 40 P-200 * The photosensitivematerial was added in an amount of 30 parts by weight per 100 parts byweight of the total of the polyimide and the polyamic acid.

TABLE 2 Film Expo- thickness sure Develop- after Water time mentdevelopment Resolution absorption (sec) time (sec) (μm) (μm) (%) Ex. 115 45 1.0 3 2.2 2 15 40 1.0 3 1.7 3 15 60 1.0 3 1.9 4 15 60 1.0 3 1.4 515 60 1.0 5 0.8 Comp. 1 40 >180 1.0 Remaining 1.9 Ex. film 2 15 0 0 —0.8 3 35 150 0.97 >30 >3 4 Impossible to obtain a uniform coating film.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to obtain a positivephotosensitive resin composition which presents a pattern having a highdimensional stability after curing without film reduction, swelling orpeeling at the time of development with an aqueous alkaline solution andof which the final cured film has a low water absorption and isexcellent in alkaline resistance.

The positive photosensitive polyimide resin composition of the presentinvention is used not only for an interlayer insulating film for asemiconductor device, a passivation film, a buffer coating film, aninsulating film for a multilayer printed circuit board, etc., but alsofor a protective film for a thin film transistor of a liquid crystaldisplay device, a protective film for electrodes for an inorganic ELdevice, etc.

1. A positive photosensitive polyimide resin composition, comprising:100 parts by weight of an organic solvent-soluble polyimide havingrepeating units represented by the formula (1):

wherein m is an integer of from 3 to 10,000, R¹ is a tetravalent organicgroup, R² is a bivalent organic group, provided that from 5 to 100 mol %of R² is a bivalent organic group having fluorine), 5 to 400 parts byweight of a polyamic acid having repeating units represented by theformula (2):

wherein n is an integer of from 3 to 10,000, R³ is a tetravalent organicgroup, and R⁴ is a bivalent organic group), and a compound capable ofgenerating an acid by irradiation with light.
 2. The positivephotosensitive polyimide resin composition according to claim 1, whereinin the solvent-soluble polyimide having repeating units represented bythe formula (1), from 90 to 100 mol % of R² is a bivalent organic grouphaving no acidic group.
 3. The positive photosensitive polyimide resincomposition according to claim 1, wherein the solvent-soluble polyimidehaving repeating units represented by the formula (1) is asolvent-soluble polyimide having a dissolution rate of at least 0.1μm/min in a 2.38 wt % tetramethylammonium hydroxide aqueous solution at23° C.
 4. The positive photosensitive polyimide resin compositionaccording to claim 2, wherein the solvent-soluble polyimide havingrepeating units represented by the formula (1) is a solvent-solublepolyimide having a dissolution rate of at least 0.1 μm/min in a 2.38 wt% tetramethylammonium hydroxide aqueous solution at 23° C.
 5. Thepositive photosensitive polyimide resin composition according to claim1, wherein in the solvent-soluble polyimide having repeating unitsrepresented by the formula (1), the four carbonyl groups bonded to R¹are not directly bonded to an aromatic ring, or R¹ is a tetravalentorganic group constituting an aromatic tetracarboxylic acid havingfluorine.
 6. The positive photosensitive polyimide resin compositionaccording to claim 4, wherein in the solvent-soluble polyimide havingrepeating units represented by the formula (1), the four carbonyl groupsbonded to R¹ are not directly bonded to an aromatic ring, or R¹ is atetravalent organic group constituting an aromatic tetracarboxylic acidhaving fluorine.
 7. The positive photosensitive polyimide resincomposition according to claim 1, which contains from 10 to 400 parts byweight of the polyamic acid having repeating units represented by theformula (2) per 100 parts by weight of the solvent-soluble polyimideresin having repeating units represented by the formula (1) and whichcontains from 1 to 50 parts by weight of the compound capable ofgenerating an acid by irradiation with light per 100 parts by weight ofthe total amount of repeating units represented by the formula (1) andrepeating units represented by the formula (2).
 8. The positivephotosensitive polyimide resin composition according to claim 6, whichcontains from 10 to 400 parts by weight of the polyamic acid havingrepeating units represented by the formula (2) per 100 parts by weightof the solvent-soluble polyimide resin having repeating unitsrepresented by the formula (1) and which contains from 1 to 50 parts byweight of the compound capable of generating an acid by irradiation withlight per 100 parts by weight of the total amount of repeating unitsrepresented by the formula (1) and repeating units represented by theformula (2).
 9. The positive photosensitive polyimide resin compositionaccording to claim 1, wherein the compound capable of generating an acidby irradiation with light is at least one compound selected from thegroup consisting of a 1,2-naphthoquinonediazido-4-sulfonic acid ester, a1,2-naphthoquinonediazido-5-sulfonic acid ester, a1,2-naphthoquinonediazido-6-sulfonic acid ester, a1,2-naphthoquinonediazido-4-sulfonamide, a1,2-naphthoquinonediazido-5-sulfonamide, and a1,2-naphthoquinonediazido-6-sulfonamide.
 10. The positive photosensitivepolyimide resin composition according to claim 8, wherein the compoundcapable of generating an acid by irradiation with light is at least onecompound selected from the group consisting of a1,2-naphthoquinonediazido-4-sulfonic acid ester, a1,2-naphthoquinonediazido-5-sulfonic acid ester, a1,2-naphthoquinonediazido-6-sulfonic acid ester, a1,2-naphthoquinonediazido-4-sulfonamide, a1,2-naphthoquinonediazido-5-sulfonamide, and a1,2-naphthoquinonediazido-6-sulfonamide.
 11. A solution having thepositive photosensitive polyimide resin composition as defined in claim1 dissolved in an organic solvent at a concentration of from 1 to 50 wt%.
 12. A solution having the positive photosensitive polyimide resincomposition as defined in claim 8 dissolved in an organic solvent at aconcentration of from 1 to 50 wt %.
 13. A cured film obtained by coatingand drying the solution as defined in claim 11 on a substrate.
 14. Acured film obtained by coating and drying the solution as defined inclaim 12 on a substrate.
 15. The positive photosensitive polyimide resincomposition according to claim 1, which comprises from 5 to 400 parts byweight of the polyamic acid having repeating units represented by thefonnula (2) per 100 parts by weight of the solvent-soluble polyimideresin having repeating units represented by the formula (1).
 16. Thepositive photosensitive polyimide resin composition according to claim1, which comprises from 50 to 200 parts by weight of the polyamic acidhaving repeating units represented by the formula (2) per 100 parts byweight of the solvent-soluble polyimide resin having repeating unitsrepresented by the formula (1).
 17. A semiconductor element comprisingan interlayer insulating film which comprises the positivephotosensitive polyimide resin composition of claim
 1. 18. A multilayerprinted circuit board, which comprises a passivation film, a buffercoating film, or an insulating film; wherein at least one of thepassivation film, the buffer coating film, or the insulating filmcomprises the positive photosensitive polyimide resin composition ofclaim
 1. 19. In an organic EL device which comprises an electrode and aprotective film for said electrode, the improvement comprises: saidprotective film comprises the positive photosensitive polyimide resincomposition of claim
 1. 20. In a liquid crystal display device whichcomprises a thin film transistor and a protective film for said thinfilm transistor, the improvement comprises: said protective filmcomprises the positive photosensitive polyimide resin composition ofclaim 1.